The invention resides in an injection molding nozzle which is installed in a base member of an injection molding tool by means of a support element which has a lower heat conductivity than the base member. The invention also relates to an injection molding tool which includes such an injection molding nozzle.
Such injection molding nozzles and injection molding tools are well-known in the art.
In order to accommodate high quality requirements, an injection molding nozzle must be installed into the base body of an injection molding tool with high accuracy. Particularly an injection nozzle with a needle valve must be installed in the base body of the injection molding tool with high accuracy, since it is important for good operation and long operating periods of an injection molding tool, that the valve needle is inserted into the discharge opening of the injection molding nozzle in a perfectly centered way. Injection molding nozzles are therefore always installed into the base body of the injection molding tool with a press fit.
With such a press-fit, a transition area with good heat conductivity between the injection molding nozzle and the base body is formed. This is disadvantageous particularly in connection with hot channel injection molding tools, since, in order to be able to manufacture an injection molding part of high quality the injection molding material is to be maintained within a hot channel nozzle at a relatively constant temperature. Particularly in connection with high-tech applications, there is only a small processing temperature window for the molding material being processed.
In order to avoid for example temperature changes of the injection molding material in the injection nozzle, often special heat sources are arranged at or near the injection molding nozzle. This however is very expensive.
If, for example, between the injection molding nozzle and the base body of the injection molding tool, a ring or a washer of a ceramic material is arranged, the heat transfer resistance between the injection molding nozzle and the base body is increased whereby the heat conduction out of the injection nozzle is decreased. However, the placement of such a ring or washer between the injection molding nozzle and the base body reduces the precision of the arrangement of the injection molding tool. With such a ceramic ring or, respectively, ceramic washer the injection molding nozzle can no longer be accurately positioned in the base body of the injection molding tool by means of a press fit.
It is the object of the present invention to provide an injection molding nozzle and an injection molding tool of the type referred to above wherein the heat transfer resistance between the injection nozzle and the base body of the injection molding tool is high and the injection molding nozzle is installed in the base body with a close fit.